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Journal of Renewable and Sustainable Energy is an online-only journal dedicated to publishing significant advances covering all aspects of renewable and sustainable energy relevant to the physical science and engineering communities. As a web-based journal with rapid publication time, Journal of Renewable and Sustainable Energy is responsive to the many new developments expected in these fields. The interdisciplinary approach of the publication ensures that the editors draw from authors from around the world across a diverse range of active and expanding fields. The journal is published online only on a bi-monthly basis (6 issues per year).

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First, the principle of the temperature drop in the air-powered engine (APE) is studied in this paper. The thermodynamic model of the APE and the calculation model for equivalent air temperatures in critical locations of the APE are proposed. Second, through the calculation by the models above, the temperature drop of the APE causes the ice blocking to influence the APE working negatively. And it is a particular problem that conventional gasoline engines will not meet. To solve the ice blocking problem without consuming additional energy out of the APE system, a heat exchange structure for the APE is designed to compensate the drop temperature and make sure the APE work efficiently. To verify the APE works in a good temperature distribution situation, some simulations are done, it is shown that the APE with the heat exchange structure works better in temperature distribution and ice blocking prevention. In addition to this, the results of simulation are verified by experiments. In conclusion, the APE with the heat exchange structure can avoid the ice blocking problem. Besides, it can help improve the APE's working efficiency by about 30%. The study provides a theoretical basis for further research on the principle of the temperature drop and heat exchange in the APE.

The effect of the molecular architecture of dye on the performance of a hemicyanine based dye sensitized solar cell(DSSC) has been studied using theoretical and experimental tools. These dyes were utilized as sensitizers in DSSC and then later were characterized using various techniques like I-V, impedance, electron transfer kinetics, dielectrics, and Tafel polarization in order to study the photovoltaic performance. The dye having a p-OH group (INS 1) exhibited very good photon to electricity conversion efficiency (3%) along with good fill factor while the dye having a p-OMe group (INS 2) lagged behind in performance. The substituent effect was studied theoretically as well as experimentally emphasizing the dipole moment of the dye in various directions. Theoretical investigation reveals that the presence of a p–OH group in the donor unit enhances the dipole moment of the molecule in comparison to a p-OMe group, thereby imparting longer lifetime of excited state leading to better charge transfer at the TiO2/dye interface.

Peak-hour tariff typically troubles commercial office buildings in hot and humid climates where cooling demands are high during summer. Because the local power company rate structure strongly favors the practice of load shift and conversely penalizes peak load demand during peak hours, a multi-functional office building in Taipei seeks to reduce its cooling cost by ways of an ice thermal energy storage system in which harvested ice is stored during cheaper off-peak hours and thawing the storage medium during peak hours. The system uses partial storage approach to satisfy off-peak cooling demand while peak-hour cooling burden is relieved by chilled water built the previous night. Two screw chillers would be integrated with each other for the implementation to allow feeding chill water to the air-handler coils while producing ice for storage at the same time. The refrigeration cycle of water chilling operates under two modes, the ice mode for thermal storage, and the chill water mode for instantaneous air cooling. Super-cooled air from melted ice-water makes humidity levels to be lower than conditioned with conventional systems, as well as load shift incentives. Cool air is introduced to variable air volume terminal boxes and is mixed with induced plenum air to bypass any reheat, yielding additional saving.

Oscillating foil machines represent a type of flow energy harvesters which perform pitching and plunging motions simultaneously to harness the energy from incoming stream. In this paper, a new adaptive deformation oscillating wing was proposed and the theoretical performance of such a concept was studied here through unsteady two-dimensional simulations using an in-house developed computational fluid dynamics code. During operation, the proposed oscillating foil whose initial shape is symmetric can be deformed into a cambered foil, which aims to produce large lift force. Our numerical results suggest that the power efficiency of the proposed oscillating foil can be about 16.1% higher than the conventional oscillating foil without deformation. In addition, the effects of the maximum bending displacement and effective angle of attack on the efficiency of proposed oscillating foil were also discussed in this work.

In this study, calibration and validation data sets from 2001 to 2005 and 2006 to 2010, respectively,
were used to develop various Angström-Prescott models: A five-year model and five-year dry
and wet seasonal models to calculate monthly average daily global solar radiation on a horizontal
surface and twelve monthly models to estimate average daily global solar radiation on a horizontal
surface. Also, ten yearly models were developed for each year in the period 2001–2010. The
regression coefficients for the
five-year, dry season, and wet season models were found to be (0.21, 0.38), (0.21, 0.38),
and (0.27, 0.28), respectively. For the twelve monthly models, and varied over the ranges 0.19–0.37 and
0.14–0.42, respectively. For the ten yearly models, and varied over the ranges 0.15–0.31 and
0.22–0.48, respectively. The regression coefficients of the twelve monthly models yielded a linear
relationship between and over a one-year time scale. Similarly,
the ten yearly models also yielded a linear relationship between and over a ten-year time scale. For all the
models,
measured and calculated daily global solar radiation were compared by calculating the mean bias
error, mean percentage error, root mean square error, correlation coefficient,
Nash-Sutcliffe efficiency, and p-values based on t-statistics. Good
agreement was found between the measured and calculated values and hence these
models
can be used in Trinidad. The single five-year model was found to be adequate in modelling the dry
and wet seasons. Using the full data set, 2001–2010, the average daily global
solar radiation,
average total global solar
radiation, average daily number of sunshine hours, and average total
number of sunshine hours were determined to be
MJ m−2 day−1,
GJ m−2,
h day−1, and
h, respectively, for the dry season;
MJ m−2 day−1,
GJ m−2,
h day−1, and
h, respectively, for the wet season; and
MJ m−2 day−1,
GJ m−2,
h day−1, and
h, respectively, for the whole year.

Latest Articles

This paper presents the results of a survey conducted at the end of a battery electric vehicle (BEV) promotional project in Taipei. Consumer attitudes toward BEVs were evaluated and analyzed. Most people are positive about BEV application, indicating that the pilot project served its promotional and educational purposes. The respondents' purchase motivations and major expectations regarding the EVs were cross-examined with their level of satisfaction. Demographic characteristics, including gender, age, education, type of job, income, residential area, and car ownership status, were selected as influential factors. No significant difference was observed for the factors applied in this study, except that residential area may have influenced the degree of satisfaction. Younger consumers generally expressed less satisfaction; however, their willingness to purchase an EV was similar to that of consumers in general. Environmental and functional values were, respectively, ranked first and second for purchase motivation. Battery charging time and maintenance cost reduction were the first two major expectations in the decision to purchase an EV. Generally, consumers tended to accept a purchasing cost increase of 25%–50% higher than that of internal combustion vehicles. Central government, the industry, and consumers were considered to have the most critical roles in promoting the EV market, whereas economic conditions, technological advancements, and policy and regulations were the most needed breakthroughs. These results reveal that crucial technological breakthroughs and effective economic and political stimulations are required to initiate a successful social transition towards using BEVs.

Improving the voltage stability in power systems is one of the most important discussions in planning and operation. Voltage stability relies on network configuration, the amount of reactive power, and the setting of reactive power compensating devices. The strong voltage stability of the wind injection buses was enhanced by inserting wind generation and thus increasing the wind penetration level in them. The power system and wind generation area have been influenced by placing new generation at these buses. The proposed method presents a suitable solution to identify the weak points of the system for each wind penetration level. The proposed method uses an index of maximum loading factor and mega watt margin in order to determine the size and the location of wind farms. This study also shows that the location of static VAR compensator has even a vital role in increasing the loading level and megawatt margin of the system. Simulations have been done in the IEEE 14-bus test system using Matlab and PSAT software.

In this paper, we have carried out detailed technical and economic assessment of perovskite solar cells for large scale manufacturing. For ultra-small area of the order of 0.1 cm2, efficiency of 20% or so are reported. However, for area of 25 cm2, the efficiency is about 10%. Based on the photovoltaic module manufacturing requirements of no constraint on the supply of raw materials, low variability of every key process and process-induced defects, low cost of manufacturing, prospects for further cost reduction in the future, green manufacturing, and long-term reliability, there are absolutely no prospects of manufacturingperovskite solar cells. No one has commercialized perovskite solar cells. Thus, contrary to hype in the literature, there is no truth that perovskite solar cells will replace silicon solar cells. We have also examined the role of perovskite solar cells for increasing the efficiency of silicon solar cells and found unsuitable both for two and four terminal device architectures.

The effects of large-scale integration of Building Integrated Photovoltaic systems on power losses in a Distribution Network (DN) have been analyzed. A comparative analysis of three different methods has been carried out. The first applied method is based on the statistical equivalent of the DN and production profiles of the Photovoltaic (PV) systems calculated from the measurement data of 10 min average values of solar irradiation taken for the period of 1 yr. The statistical equivalent of the DN is estimated based on hourly measurements of the injected power in the DN and billed electrical energy. The estimated equivalent statistical resistance is used for DN modeling for the purpose of calculating power losses. Fuzzy numbers are used as the second method of the research for the purpose of faster estimation. The Monte Carlo simulation, as the third method, is used to involve all possible situations of PV production and energy consumption. The economy calculation is made based on the results of power losses' reduction in the DN of Serbia. The proposed methodology is of a general character; however, it can be applied to other power distribution systems.

Fully hydraulic wind power generation is an emerging research direction. These hydraulic wind power generators replace the rigid connection between wind turbine and generator with a hydraulic flexible transmission system. This effectively absorbs a majority of the fluctuating load from the wind turbine, thereby achieving step less speed change and enabling the generator within the unit to maintain stable rotational speeds. The fully hydraulic wind power generator is different from the traditional wind power generators in terms of the transmission system used. As a result, the research here is focused on the transmission characteristics of the hydraulicsystem. Moreover, the transmission characteristics of the fully hydraulicwind turbine were compared to wind turbines with a mechanical transmission, from the analysis of the comparison different operating characteristics were revealed. The experiments using a test bench to study the full hydraulic wind power generator, whereas simulations using a model were carried out for the wind power generator with the mechanical transmission.

The microalgae biomass, mainly rich in lipids, carbohydrates, and other groups of compounds, has been considered as a promising raw material for renewable fuels production, particularly biodiesel. However, further knowledge on this subject is still needed. The objective of this study was to evaluate the effect of culture growth conditions (nutrient fractionation) on the cell biomass levels, fatty acid profile, as well as the content of fatty acids methyl esters (FAME) of freshwater microalgae Choricystis minor var. minor. The experiment consisted in determining the culture growth (biomass levels) employing WC medium in two treatments: full initial addition (100%) and fractional addition of nutrients on three specific days. The biomass produced was harvested in the exponential and stationary phases of the growth curve. No significant differences were found in the biomass levels (approximately 0.5 g l−1 at 8 days of culture) using different treatments. The FAME yields varied between 213.7 and 276.8 mg g−1 of dry biomass. Regarding the qualitative composition, fatty acid profiles were similar under tested culture growth conditions, whereas the quantitative content changed between them. The results from this investigation suggested that cultivation with full initial nutrient addition and biomass harvested at the stationary phase provided higher FAME yield and lower tri-unsaturated fatty acids (9.6%) and polyunsaturated fatty acids (4.0%) levels. Because of these characteristics, this culture growth conditions represent, among the studied strategies, the most interesting for Choricystis minor var. minor cultivation in order to produce biodiesel.